1999Porsche911

And, just WHY is it different with ABS?

wrljet

Because in the normal steady state of the system, the valving in the ABS modulator is such fluid passes from the master cylinder to the wheel cylinders, bypassing a maze of twisty little passages in the modulator.

If the ABS is never activated there are places in there where the fluid could be sitting for years.

1999Porsche911

And you can't think of a simple solution to this?

wrljet

Sure, get the ABS to exercise itself or use the PST2.

wrljet

But that wasn't my point.

I was simply saying this post wasn't completely correct in the context of ABS:

Tippy

Wow, I am confused now. So the PST2 opens the ABS tracts and releases old fluids?

evansaero

1999Porsche911 is correct in saying that you only need 3 gallons of the stuff

IMHO I only like to use what porsche approves... If you go to your VW/Audi dealer you can pick up the same coolant that porsche uses and its half the price. G12 coolant (Red/pink color) from VW/audi part dept. Total cost was $58 for 3 gallons of the stuff.

The C4 holds 5.95 gallons of the coolant

wrljet

I've tried to attach a diagram of an ABS fluid circuit. It's a Bosch system, but I don't know which one. I added a blue line to show the flow from master cylinder to caliper when the system is in the idle state.

Bill

SteveFromMN

I changed my brake fluid two years ago using a Motive Power Bleeder. http://www.motiveproducts.com/
Used instructions per shop manual. Worked like a champ. Don't forget to bleed clutch as well. It is part of the same system.

Easy

Tippy

I thought the ABS just blocks the input side of the fluid with valves, when in it is in a static state, it is completly open and fluid passes right through without residual fluid trapped?

BruceP

Just in case you're counting votes (I don't really want to debate it), I flush and fill both coolant and brake fluid every two years on my cars. Brake fluid is affected more by age than mileage, and on low mileage cars that sit a lot, its hydrophilic property can cause decay in the lines and poorer brake performance (since water doesn't behave the way brake fluid does under pressure). If your car has not had brake fluid replaced in, say, four years, I'll bet a case of beer you can feel the difference through the pedal when you do it. Seriously.

I use whatever stupid expensive Gucci performance brake fluid my indy recommends because I am an idiot. For coolant, I use Porsche's product. The reason is that it's simple, frankly. As Land Rover owners know, inadvertently mixing the wrong kinds of anti-freezes can cause the coolant to gel. I'm sure lots of you guys are smart enough to avoid this, but I just can't be bothered honestly.

996 C4S

guys

Thank you all for all the info!!! I am now a bit confused with ABS PSM involvong brake flush, I thought the instruction from Renntech diy was straight forward. And it mentioned all we need is one liter for brake fluid.

As for the coolant most of you recoomend 3 gallons mixing with water for 50/50 total 6 gallons.

Do most of you really believe lifetime coolant on these cars??? Hard to accept!!

Thanks
Bill

1999Porsche911

Just follow the DYI and move on. No worries. The is no such thing as a lifetime coolant in any internal combustion engine. Leave it in long enough and your metal outlets will clog and/or the acid will eat through your engine.

Use whatever coolant is convenient for you. I use the 50/50 Peak Lifetime as it 100% compatable, saves time and is as good as and a fraction of the exaggerated price of Porsche's coolant. If you would use it in your Honda or Toyota or any other late model car, it is more than good enough for your Porsche.

Loren

I personally do not open the valves in the ABS when I flush and bleed my brakes/clutch - and I own a PST2. I really don't think it is needed unless the system has had a leak and drawn in air. Or, unless you are changing to a synthetic brake fluid - where you really do want to replace "all" the fluid in the system.

The coolant question and discussion can go on forever - I think if your system has been kept closed and is not contaminated in any way - then your coolant likely does not need to be changed for maybe 100,000 miles. This newer organic coolant is very good stuff. All this IMHO of course...

munro86

What "newer organic coolant" doest thou refer Loren?